False-positive warnings for checks: Unused parameter, Null assignment, Variable shadowing, While true loop, Empty if expression #466

Stardust1225 · 2020-12-26T05:14:15Z

I use scapegoat in project akka/akka, and find more than 90% of warnings from this five checks are not what I need.
1. Unused parameter
when the code is like:

case class A{
    def method(a: String, b: Int) = {
        a = "hello world in method 1"
    }

    def method(a: String) = {
        a = "hello world in method 2"
    }
}

Check Unused parameter would throw warning for parameter b in method. However, I think that b serves as a chooser for the two methods.

2. Null assignment
I think that if assign null to a var, it would not be warned for the var cannot be modified.

3. Variable shadowing
When the code is like:

case class A(a: String){
    def method(a: String) = {}
}

this check would throw warning for var a. But in this situation, a in method would not cover the class variable a, which can be distinguished by a and this.a.

4. While true loop
If there exists return statement in a while true loop, there exists a path to end this loop, and .

5. Empty if expression
If code is like:

if( bool expresion ){}
else{}

and else block is not empty, I think that the empty if block just serves to skip condition judgment, or it is easy to write conditions in if part.

The text was updated successfully, but these errors were encountered:

mccartney · 2021-01-02T20:51:47Z

(Edited your text for formatting, I hope you don't mind)

mccartney · 2021-01-02T21:00:06Z

As to the actual suggestions:

re 1 - I think the standard solution to this is to avoid overloading in such case, i.e. name the methods differently. What is the real-life use-case for sticking to overloading? Can you give a more realistic example?
re 2 - I am not fully sure I understand. I observe a lot of these null assignments false-positives (or matter of taste) myself. I am not fully sure if the same is meant though. "My" usages are around passing null as arguments to Java methods or methods which interface with Java deeper in the stack.
re 3 - I don't agree to be honest. a is shadowing a, the name a is ambiguous. The fact there's a way to point to the class-one doesn't make the a reference unambiguous.
re 4 - I suppose you are missing some text at the end of the entry
re 5 - that arguably makes sense. I think people suggest that negating the original condition in most of the cases is not much of a pain. Thus:

if (even || a && complicated.boolean.condition()) {
// no code
} else {
// a lot of code
}

is convertable to

if (!(even || a && complicated.boolean.condition())) {
// a lot of code
}

Stardust1225 · 2021-01-12T09:19:03Z

I miss some description in While True loop

while( true ){
    // wait for a thread to return value.
    if( some condition )
        return // or break 
    else
        thread.sleep(5000)
}

If the code serves as polling, and has return or break in the loop, I don't think it should be warned.``

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False-positive warnings for checks: Unused parameter, Null assignment, Variable shadowing, While true loop, Empty if expression #466

False-positive warnings for checks: Unused parameter, Null assignment, Variable shadowing, While true loop, Empty if expression #466

Stardust1225 commented Dec 26, 2020 •

edited by mccartney

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mccartney commented Jan 2, 2021

mccartney commented Jan 2, 2021

Stardust1225 commented Jan 12, 2021 •

edited

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False-positive warnings for checks: Unused parameter, Null assignment, Variable shadowing, While true loop, Empty if expression #466

False-positive warnings for checks: Unused parameter, Null assignment, Variable shadowing, While true loop, Empty if expression #466

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Stardust1225 commented Dec 26, 2020 • edited by mccartney Loading

mccartney commented Jan 2, 2021

mccartney commented Jan 2, 2021

Stardust1225 commented Jan 12, 2021 • edited Loading

Stardust1225 commented Dec 26, 2020 •

edited by mccartney

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Stardust1225 commented Jan 12, 2021 •

edited

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